The invention relates to an axial piston machine with a tiltable, rotating cylinder drum and a drive-connected drive pulley stationarily supported in a casing, pistons movable in cylinder bores of the drum being articulated to the drive pulley via ball and socket joints, and with a control mirror member with control ports (reniform) which face the outlets of the cylinder bores, the control mirror member being tiltable by an adjusting device to adjust the stroke of the pump, and whose cylinder surface shaped rear side facing away from the control mirror is supported on a suitably shaped slideway of the casing which has orifices connected with suction and pressure ducts for the pressure medium, the orifices being connected via ducts with the reniform control ports in all positions of tilt of the control mirror member, as well as a central pivot supported on the drive pulley for centering the cylinder drum, the pivot extending in a central bore of the cylinder drum and supported against the cylinder drum via an intermediately located compression spring.
This type of machine has become known, for example, from German Laid-Open Application No. 2,313,575. They are particularly suitable for small scale closed drives and excell by a noiseless and low vibration running even at high pressures and speeds. However, limitations are imposed on the possible angle of tilt of the cylinder drum in relation to the axis of the drive shaft for adjusting the stroke of the pump. Since the orifices disposed in the slideway for the control mirror member (which orifices are connected with the suction and pressure ducts of the pump) must be in alignment with the ducts in the control mirror member over the entire range of tilt of the control mirror member (which ducts are connected with the reniform control ports), said orifices must simultaneously be sealed off by the mirror member in all its positions of tilt against the interior of the machine casing.
It would be possible to enlarge the mirror member in order to achieve covering over a larger range of tilt, but the fact that the compression forces acting on the rear side of the mirror member facing the slideway must not be greater than the forces which keep the mirror member in engagement with the slideway speaks against an enlargement of the orifices on the rear side of the mirror member. These forces are exerted by the pistons via the cylinder drum onto the control mirror, that is, on the front of the mirror member and, together with the slight forces, which are exerted by the pressure spring acting between the central pivot and the cylinder drum, prevent a lifting of the mirror member from the guide surface.
In the case of the construction which has become known from German Published Application 1,017,468, the lifting forces acting on the mirror member are compensated with the aid of rollers holding down the mirror member in the slideway. This is very expensive from the point of view of construction and leads to the danger of the mirror member becoming locked, particularly in the case of wider angles of tilt.
The problem of enlargement of the angle of tilt in these types of machines is dealt with in German Laid-Open Application No. 2,003,851. There, to control the lifting forces of the mirror member, an additional special support is provided for the cylinder drum. In order to prevent the orifices between the mirror member and the suction and pressure ducts from becoming too large, and in order to control the lifting forces and still ensure a sealing covering even at wider angles of tilt, an intermediate element is interposed between the mirror member and the casing or its slideway, intermediate conduits extending through said intermediate element and the latter being tilted along with the cylinder drum over a correspondingly narrow angle of tilt. This construction requires considerable structural expenditure and leads to the need for numerous additional sealing surfaces between machine parts which move in relation to each other and are under high pressure.